In all the noise and hype around Motorola’s announcement last week of the Moto X phone, one very interesting new capability was generally overlooked: You can use random Bluetooth devices instead of passwords to unlock the phone.

Wait, what?

The feature is called “Trusted Devices.” Here’s how it works.

Inside the phone’s “Security” settings, you enter the security PIN you’ve already established, and all nearby Bluetooth devices appear. You simply pair them as if you were going to connect to and use them. These can include the wireless keyboard you use in your office with your desktop PC, the Bluetooth headset you use either with the Moto X or with some other device. You can even pair your car audio system, if you’ve got one that supports Bluetooth.

Once paired, these other devices will replace your PIN on your device if they’re within range. So once you’ve connected every device in your home, car and office, it’s like your phone doesn’t have a PIN. But once the phone is outside the range of all other devices, the PIN is activated.

This is just the latest and, in my opinion, greatest of a series of new products that are using gadgets to magically replace passwords for smartphones.

In fact, the Moto X even has another option coming soon. The company says they’re planning to release soon an NFC “token” that similarly unlocks the Moto X. NFC stands for “near field communication.” It’s a very short-range wireless technology built into some phones that requires the connecting devices to be within a few inches of each other. The lightweight plastic token clips to your shirt, coat, pants or can be placed on a desk—anywhere you like, really—and by waving the phone near the token, you unlock it, bypassing the PIN password.

NFC to Unlock Has a Nice Ring to It

A project in development called the NFC Ring is being crowd-funded on Kickstarter. The ring has two NFC unlocking features. On one side of the ring, you can unlock public devices. On the other side, private ones. (Basically, it’s a “fist-bump” to unlock public locks and a “high-five” to unlock your smartphone.)

A Shanghai China-based company called Shanda has a similar device. Called the Geak Ring, the gadget uses NFC to unlock specific Android smartphones.

“Geak Ring” is probably an apt name. The main downside to ring-based authentication gadgets is that—who wants to wear a ring designed by a technology company? A wristwatch, on the other hand...

Watch This Space

I believe the ultimate password replacement gadget will be the smartwatch. (In fact, smartwatches can already be used to unlock the Moto X).

The reason is that a watch is a highly personal device you’re likely to wear every day, all day.

The current leading smartwatch, called the Pebble, can be used to unlock smartphones, but only by using a downloadable app. Called Pebble Locker, the app both enables and disables your smartphone’s lock screen when it’s near and not near, respectively.

That means when it’s near the phone—as in near you—your phone works without a PIN or passcode. When you’re separated from the phone, it’s locked.

Apple is rumored to be working on a smartwatch, generally referred to as the iWatch, which may even have an embedded fingerprint reader, according to one analyst who recently toured suppliers for Apple in China. The combination of a wristwatch you wear all the time and which can be authenticated with biometric ID means that, in addition to unlocking your iPhone, the watch might also authenticate credit card purchases and other more serious uses. It could also provide secure access to buildings and enable you to have a kind of “E-Z pass” to every site on the Internet, if combined with an online password manager that works with the smartwatch.

Speaking of wristwatches that support the iPhone, a new product will begin shipping in Apple Stores this week called the called Shine from a startup called Misfit.

Shine is basically an activity tracker you can wear as a watch or as some other kind of accessory (you choose the wearing method by your selection of accessories on the web site, which are sold separately).

What’s amazing about the Shine is that it somehow connects to and syncs with the iPhone wirelessly and without a password. Just place the round Shine gadget on the screen, and the phone detects the device and syncs the data. An on-screen animation even shows that the phone knows exactly where on the screen the Shine sits. It even syncs when the iPhone is in Airplane Mode. (Note that the iPhone does not have NFC capability.)

How do they do that?

A promotional video by the company claims that Shine uses “a new type of wireless sync technology.” Because the screen detects the location of the device, Shine probably either transmits data through capacitive charge—basically using the same phone features that detect a human finger—or a combination of capacitive and some other wireless technology—including even something that transmits data through sound above the frequency detectable by human ears.

Mysteries are rare in consumer electronics, and the Shine data transmission technology is still a mystery. Either way, they’ve found a way to bypass the normal pairing and passwords normally required for devices to send data to a phone.

Nobody likes passwords. They’re time consuming. It’s easy to get them wrong. And they separate us from quick access to the stuff we’re trying to get at on our phones.

That’s why it’s great to see the industry experimenting with new ways to get rid of them, using nearby gadgets instead.